Photographic elements and processes

ABSTRACT

A SILVER PRECIPITATING LAYER IS COATED OVER OR UNDER FINEGRAIN RELATIVELY SLOW SPEED SILVER HALIDE EMULSION LAYERS, AND THESE LAYERS ARE COATED OVER A FASTER IMAGE-FORMING SILVER HALOIODIDE IMAGE-FORMING EMULSION LAYER. THE SILVER PRECIPITATING LAYER, WHEN COATED BETWEEN THE FINE-GRAIN, SLOW SPEED SILVER HALIDE EMULSION AND THE FASTER IMAGEFORMING SILVER HALOIODIDE EMULSION LAYER, REDUCES MIGRATION OF SOLUBLE SILVER SALTS OUT OF THE FINE-GRAIN SILVER HALIDE INTO THE IMAGE-FORMING EMULSION LAYER. WHEN COATED OVER THE FINE-GRAIN SILVER HALIDE EMULSION LAYER, THE SILVER PRECIPITATING LAYER INHIBITS DIFFUSION OF SOLUBLE SILVER SALTS OUT OF THE ELEMENT DURING PROCESSING, AND THEREBY REDUCES THE RATE AT WHICH SILVER DEPOSITS ARE BUILT UP ON ROLLERS USED IN EQUIPMENT WHICH TRANSPORTS THE FILM THROUGH PHOTOGRAPHIC PROCESSING SOLUTIONS.

United States Patent 3,737,317 PHOTOGRAPHIC ELEMENTS AND PROCESSES Robert D. Nicholas and James D. Clitlord, Pittsford, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y. No Drawing. Filed Apr. 12, 1971, Ser. No. 133,444 Int. Cl. G03c 1/48, 1 76, 3/00 US. Cl. 96-74 12 Claims ABSTRACT OF THE DISCLOSURE A silver precipitating layer is coated over or under finegrain relatively slow speed silver halide emulsion layers, and these layers are coated over a faster image-forming silver haloiodide image-forming emulsion layer. The silver precipitating layer, when coated between the fine-grain, slow speed silver halide emulsion and the faster imageforming silver haloiodide emulsion layer, reduces migration of soluble silver salts out of the fine-grain silver halide into the image-forming emulsion layer. When coated over the fine-grain silver halide emulsion layer, the silver precipitating layer inhibits diffusion of soluble silver salts out of the element during processing, and thereby reduces the rate at which silver deposits are built up on rollers used in equipment which transports the film through photographic processing solutions.

This invention relates to photography and more particularly to novel photographic elments and processes.

Silver haloiodide emulsions are highly desirable in photographic materials and processes because of the increased photographic speeds, longer Wavelength spectral response and desirable interimage efiects obtained as a result of the presence of iodide in the silver halide grain. However, the iodide in the silver haloiodide emulsion can cause problems during photographic development due to the release of iodide, particularly when developing solutions are employed which contain substantial amounts of silver halide solvent, such as sodium sulfite or sodium thiocyanate. The release of iodide in developer solutions is highly undesirable because iodide inhibits development, and adversely affects the sensitometric properties of the material being procesed.

It has been found that substantially iodide-free silver halide Lippmann emulsions (i.e., fine-grain silver halide emulsions of low light sensitivity) coated over the silver haloiodide emulsion layers inhibit release of iodide from light-sensitive image-forming layers into the processing solutions. The Lippmann emulsions apparently function as an iodide sink by a simple displacement reaction in Which iodide released from the silver haloiodide lightsensitive emulsion layers replaces a bromine or chlorine atom in the silver halide of the Lippmann emulsion. Bromide or chloride ions are released from the Lippmann emulsion, but these ions are much less detrimental in processing solutions than iodide ions. Elements of this general type are known in the literature. See, for example, French Pat. 912,605.

Photographic materials can contain various compounds which release development inhibitors other than iodide development inhibitors. Such compounds include those described in Whitmore et al. US. Pat. 3,148,062 issued Sept. 8, 1964 and Barr et al. US. Pat. 3,227,554 issued Jan. 4, 1966. Lippmann emulsions prevent release of such development inhibitors into photographic processing solutions. These development inhibitors apparently are adsorbed on the silver halide grains of the Lippmann emulsion.

While the Lippmann emulsion overlayer solves the problem of the release of iodide into developer solutions, the Lippmann emulsion itself can introduce other prob- Patented June 5, 1973 lems in photographic elements and processes. Thus, when such elements are drawn through developer solutions containing silver halide solvent using roller transport equipment (e.g., a machine as described in Russell et al. U.S. Pat. 3,025,770 issued Mar. 20, 1962), the silver of the Lippmann emulsion tends to dissolve out of the photographic element and plate out on the transport rollers. Silver deposits on the transport rollers cause abrasion of the element being processed. The entire processing operation must be shut down and the processing rollers must be cleaned or replaced before the silver deposit damages the film being processed.

Another problem occurs with silver haloiodide emulsions having an overcoating comprising a Lippmann emulsion When the silver halide of the Lippmann emulsion dissolves and the soluble silver salts migrate into the lightsensitive emulsion layer and produce unwanted photographic images. Although hte Lippmann emulsion is very much slower than the light-sensitive silver haloiodide emulsion layer, chemical fogging or intense exposures render developable any soluble silver salts from the Lippmann silver halide present in the image-forming silver haloiodide emulsion layers. This problem arises, for example, when soluble silver salts from the Lippmann emulsion dilTuse into an image-forming silver haloiodide emulsion layer during reversal processing using initial black-andwhite or MQ developers which contain silver halide solvent. The undeveloped silver halide is then fogged with light or chemical fogging agents, and dye images are generated in direct or reverse proportion to the reversal silver image in the image-forming silver haloiodide containing layers. Thereafter, all the silver in the element is bleached out. In such processes, the Lippmann emulsion interferes only when the soluble silver salts formed therein migrate into the image-forming silver haloiodide emulsion layer and are reduced by the color developer to form undesirable dye density. The development of silver in the Lippmann emulsion layer is not harmful since no coupler is present in the Lippmann emulsion layer and therefore no dye is formed in that layer.

Accordingly, it is one object of this invention to provide photographic elements which have reduced tendency to release iodide or other development inhibitors in photographic developer solutions.

Another object of this invention is to provide photographic elements which have reduced tendency to cause silver deposits on roller transport equipment employed in photographic processing.

A further object of this invention is to provide photographic elements in which soluble silver salts from the fine-grain silver halide overcoating layers have reduced tendency to migrate into light-sensitive image-forming silver halide emulsion underlayers.

Still another object of this invention is to provide improvements in photographic processes which employ roller transport equipment to process exposed photographic films.

Another object of this invention is to provide photographic processes which utilize silver halide solvent in developer solution.

Other objects of this invention will be apparent from this disclosure and the appended claims.

In one embodiment of this invention, photographic elements comprising a support having coated thereon a light-sensitive photographic silver haloiodide emulsion feature a fine-grain silver halide emulsion layer, the halide of the fine-grain silver halide consisting essentially of chloride and bromide, the grain size of the fine-grain emulsion being less than about .1 micron and the speed of the fine-grain emulsion being at least 50 times slower than the light-sensitive silver haloiodide emulsion; and,

in combination with the fine-grain silver halide emulsion layer, a silver precipitating layer. Both the silver precipitating layer and the fine-grain silver halide emulsion layer are coated over the light-sensitive silver haloiodide layer.

In another embodiment of this invention, a photographic process is provided wherein an exposed photographic element is developed in the presence of a developer solution comprising silver halide solvent, and the photographic element is transported through the developer solution by the use of work advancing rollers immersed in the developer solution, which photographic element comprises a support having coated thereon a light-sensitive silver haloiodide emulsion, an overlying silver precipitating layer and, between the silver precipitating layer and the silver haloiodide emulsion layer, a finegrain silver halide emulsion layer, the halide of the finegrain Silver halide consisting essentially of chloride and bromide, the size of the fine-grain emulsion being less than about .1 micron and the speed of the fine-grain emulsion being at least 50 times slower than the light-sensitive silver haloiodide emulsion.

In another embodiment of this invention, a photographic process is provided wherein an exposed photographic element is developed to provide an initial silver image, a reversal silver image is developed and dye is generated in proportion to the reversal silver image, and the silver images are removed from the element, said element comprising a support having coated thereon a light-sensitive photographic silver bromoiodide emulsion layer, an overlying silver precipitating layer and a finegrain silver halide emulsion layer, the halide of the finegrain silver halide consisting essentially of chloride and bromide, the grain size of the fine-grain emulsion being less than .1 micron and the speed of the fine-grain emulsion being at least 50 times slower than the light-sensitive silver haloiodide emulsion. The silver precipitating layer is coated between the fine-grain silver halide emulsion layer and the light-sensitive silver bromoiodide emulsion layer.

A silver precipitating layer coated over a fine-grain silver halide emulsion layer, which in turn is coated over an image-forming silver haloiodide layer, effectively reduces the rate at which undesirable silver deposits build up on the rollers used in transporting the material through developer solutions containing silver halide solvent.

A .silver precipitating layer coated between a fine-grain silver halide emulsion layer and an image-forming silver haloiodide emulsion layer effectively reduces the undesirable migration of the fine-grain silver halide into the image-forming emulsion layer. 'If desired, silver precipitating layers can be coated on both sides of the finegrain silver halide emulsion layer.

Typical photographic elements in accordance with the invention can comprise one of the following layer arrangements on a suitable support:

Fine-grain, slow speed silver halide emulsion layer Silver precipitating layer Image-forming silver haloiodide emulsion layer Support Silver precipitating layer Fine-grain, slow speed silver halideemulsion layer Image-forming silver haloiodide emulsion layer Support layer arrangement of a preferred photographic element is indicated below:

(9) Silver precipitating layer (8) Fine-grain silver halide emulsion (7) Blue-sensitive silver bromoiodide emulsion plus yellow-forming coupler (6) Gelatin interlayer plus yellow filter (5) Green-sensitive silver bromoiodide emulsion plus magenta-forming coupler (4) Gelatin interlayer (3) Red-sensitive silver bromoiodide emulsion plus cyanforming coupler (2) Antihalation 1 Support If desired, in above film C, layers 8 and 9 can be reversed, or a separate silver precipitating layer can be inserted between layers 8 and 9. Also, the light-sensitive layers 3, 5 and 7 can contain fast and slow speed silver bromoiodide emulsion layers.

The silver precipitating layer can comprise any suitable material which does not exert adverse etfects on the photographic element and which effectively precipitates silver. Typical useful silver precipitating agents for use in the silver precipitating layer include metal sulfides, metal selenides, metal polysulfides, metal polyselenides, thiourea, stannous halides, heavy metals and heavy metal salts, and fogged silver halide. Heavy metal sulfides such as lead, silver, zinc, antimony, cadmium and bismuth sulfides are useful, particularly the sulfides of lead and zinc alone or in admixture, or complex salts of these with thioacetamide, dithio-oxamide, or dithio-buret. The heavy metals include silver, gold, platinum, and palladium preferably in the colloidal form. The noble metals are particularly efiicacious. Carey Lea silver, which has a typical particle size of from .1 to .001 micron, is particularly useful.

The amount of silver precipitating agent used in the silver precipitating layer can be any amount which effectively reduces migration of silver or silver halide through the silver precipitating layer. When it is desirable to expose the image-forming layer through the silver precipitating layer, the amount and size of precipitating agent should be chosen to allow free transmission of light. The effective amount of precipitating agent depends primarily on the particle size and activity of the nuclei and the quantity of silver ion that must be precipitated. Generally, about 8 10tto 1.0 10 moles of precipitating agent per square foot provides satisfactory reduction in the silver or silver halide migration through the silver precip itating layer. The silver precipitating agent can be incorporated in any suitable binder, e.g., a hydrophilic colloid such as gelatin. The thickness of the silver precipitating layer may vary widely with good results generally being obtained with silver precipitating layers having a thickness on the order of .0005 to .002 millimeter. When gelatin in employed as binder, preferred coating coverages range from about 50 to 150 mg. of gelatin per square foot.

As already indicated, the silver precipitating layer can be coated over or under the fine-grain slow speed silver halide emulsion layer utilized in elements and processes of this invention. If desired, the silver precipitating layer can be coated on both sides of the fine-grain slow speed silver halide emulsion layer. The silver precipitating layer is advantageously juxtaposed and co-extensive with the fine-grain slow speed silver halide emulsion layer.

In accordance with the invention, the fine-grain slow speed silver halide emulsion layer utilized herein has an average grain size less than about .1 micron and is about 50, and preferably about times slower in photographic speed than the image-forming silver halide emulsions utilized in the elements and processes described herein. The halide of such fine-grain silver halide emulsions preferably is essentially free from iodide. Fine-grain silver chloride, silver bromide or silver chlorobromide emulsions provide highly satisfactory results. Preferably the halide in the fine-grain silver halide emulsion layer contains less than mole percent iodide.

The fine-grain silver halide emulsion effectively reacts with iodide released from the image-forming silver haloiodide emulsion layers, and thus inhibits iodide contamination of processing solutions. The fine-grain silver halide emulsion layer can also effectively inhibit contamination of processing solutions by other photographic addenda, such as the inhibitors released by devolpment inhibitor releasing couplers.

The fine-grain silver halide emulsion layer can be coated at various coverages of silver, such as from to 150 milligrams per square foot and preferably from to 75 milligrams per square foot.

The image-forming silver halide emulsion layers utilized in the elements and processes of this invention comprise iodide. The elements and processes of the invention are useful when the image-forming layer contains any quantities of iodide. Typical useful emulsions often contain up to 10 mole percent iodide with the remainder of the halide being chloride or bromide. It is desirable to use silver halides which have a halide content of at least 50 mole percent, and preferably at least 80 mole percent bromide, and up to 10 mole percent iodide, an'y remaining halide being chloride. Typical preferred iodide contents range from about 1 to 8, and preferably 2 to 5, mole percent iodide. The coverage of the image-forming silver haloiodide emulsion layer will in large part determine the optimum thickness and concentration of the addenda in the fine-grain slow speed silver halide emulsion layer and the silver precipitating layer. The imageforming silver haloiodide grains can be any suitable size or shape. Generally, average grain size of over about .8 micron is preferred.

The present invention is particularly suited to processing films of the type described herein in developer solutions which utilizes silver halide solvent. Typical silver halide solvents commonly employed in developers are the alkali thiosulfates, thiocyanates and cyanides; thioureas; thioethers; and, ammonium hydroxide. Sodium, thiosulfate and sodium thiocyanate are particularly useful silver halide solvents. The elements and processes of the invention are especially useful when relatively high concentrations of silver halide solvent, such as an amount of silver halide solvent equivalent in activity to developer solutions containing 1 to 5 grams, and preferably 1.5 to 3 grams sodium thiocyanate per liter of developer solution, are utilized.

The image-forming silver haloiodide emulsion layers employed in the elements and processes of this invention can contain chemical sensitizers, spectral sensitizers, speed-increasing compounds, plasticizers, hardeners and coating aids, and the silver halide grains can be dispersed in gelatin or other colloids, such as the addenda and hydrophilic colloids described and referred to in Graham et al. U.S. Pat. 3,046,129 issued July 24, 1962, columns 20-23. Also, the fine-grain silver halide and the silver precipitating agent can be dispersed in any suitable colloids, such as those referred to by Graham et al., supra, column 22.

As used herein, when a first layer is referred to as being coated over a second layer, over means that the first layer is coated in such a manner that the second layer is between the first layer and the support. Other layers can be coated between, over or under such layers.

The following examples are included for a further understanding of the invention.

EXAMPLE 1 An incorporated coupler film is prepared as described by Graham et al. U.S. Pat. 3,046,129, Example (a), column 27, the halide of the silver bromoiodide emulsion layers containing about 3 mole percent iodide, and coating over the emulsion layers a fine-grain slow speed Lippmann silver bromide gelatin emulsion having an average grain size between about .01 to .05 micron and being more than about times slower than the underlying silver haloiodide emulsion layers, said Lippmann emulsion being coated at a coverage of about 49 milligrams of silver per square foot and 100 milligrams of gelatin per square foot; and, coating over said fine-grain silver halide emulsion, at gelatin layer containing Carey Lea silver at a silver coverage of about .15 milligram per square foot and a gelatin coverage of 100 milligrams per square foot. The photographic element obtained is developed with the reversal color process as described in Graham et al. U.S. Pat. 3,046,129, column 23, which process employs about 1.5 grams sodium thiocyanate (silver halide solvent) per liter of MQ developer solution. Processing is conducted using the roller transport equipment described in Russell U.S. Pat. 3,025,779 issued Mar. 20, 1962. It took approximately 9 to 10 hours of continuous operation before the silver deposits built up sufliciently on the transport rollers in the MQ developer to require shutdown and cleaning of the rollers. When a control is prepared and processed in exactly the same manner, except omitting the silver precipitating layer, the transport rollers in the MQ developer have a sufficiently large coating of silver deposits to necessitate cleaning or replacing after 2 to 3 hours of continuous operation. Generally similar results are obtained when other silver precipitating agents are substituted for the colloidal silver, such as colloidal palladium, thiourea or zinc sulfide.

EXAMPLE 2 An incorporated coupler film, Coating 1, is prepared exactly as described in Example 1 except that the silver precipitating overcoating is omitted. This coating, which is a control, is compared with Coating 2, which is pre pared in exactly the same way except that directly beneath the fine-grain Lippmann emulsion layer there is coated a layer containing gelatin and colloidal silver in a concentration of about 0.15 milligram per square foot silver and 100 milligrams per square foot gelatin. This is referred to in Table 1 below as Coating 2. Coating 3 is prepared exactly the same as Coating 2 except that the Carey Lea silver is coated at a coverage of about 0.30

In Table 1, A blue density refers to the amount of yellow dye formed in the blue-sensitive silver bromoiodide layer as a result of the unwanted diffusion of soluble silver salts from the Lippmann emulsion into the blue-sensitive silver bromoiodide layer. During reversal processing, it appears that these soluble silver salts in the blue-sensitive silver bromoiodide emulsion layer are reduced by color developing agent, and that color developing agent reacts with the yellow dye-forming coupler to produce unwanted yello-w dye. The above example demonstrates that the silver precipitating agent effectively inhibits the fine-grain silver halide emulsion from causing undesired density in the silver haloiodide layer underlying the fine-grain silver halide emulsion layer.

The invention has been described in detail with particular reference to preferred embodiments thereof, but, it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

We claim:

1. A photographic element comprising a support having coated thereon a light-sensitive photographic silver haloiodide emulsion, a silver precipitating layer and a finegrain silver halide emulsion layer coated over the lightsensitive silver haloiodide layer, the halide of the finegrain silver halide consisting essentially of chloride and bromide, the grain size of said fine-grain emulsion being less than about .1 micron and the speed of said fine-grain emulsion being at least 50 times slower than said lightsensitive silver haloiodide emulsion.

2. A photographic element comprising a support having coated therein three light-sensitive silver haloiodide emulsion layers, said layers being responsive to blue, green and red radiation and comprising, respectively, photographic couplers which form yellow, magenta and cyan dye upon reaction with oxidized color developing agent, a silver precipitating layer and a fine-grain silver halide emulsion layer coated over said light-sensitive silver haloiodide emulsion layers, the halide of the fine-grain silver halide consisting essentially of chloride and bromide, the grain size of said fine-grain silver halide emulsion be ng less than about .1 micron and said fine-grain silver halide emulsion being at least about 50 times slower than the silver haloiodide emulsion in said light-sensitive layers.

3. A photographic element comprising a support having coated thereon three light-sensitive silver haloiodide emulsion layers, said layers being responsive to blue, green and red radiation and comprising, respectively, photographic couplers which form yellow, magentaand cyan dye upon reaction with oxidized color developing agent, a silver precipitating layer; and, a fine-grain silver hal de emulsion layer, the halide of the fine-grain silver halide consisting essentially of chloride and bromide, the grain size of said fine-grain silver halide emulsion bemg less than about .1 micron and said fine-grain silver halide emulsion being at least about 50 times slower than the silver haloiodide emulsion in said light-sensitive layers, said fine-grain silver halide emulsion layer being coated over said light-sensitive silver haloiodide emulsion layers and under said silver precipitating layer.

4. A photographic element comprising a support having coated thereon, in the order given, a red-sensitive silver bromoiodide emulsion layer containing a cyan dyeforming photographic coupler; a green-sensitive silver bromoiodide emulsion layer containing a magenta dyeforrning photographic coupler; a yellow filter layer; a bluesensitive silver bromoiodide emulsion layer contammg a yellow dye-forming photographic coupler; a fine-grain silver bromide, silver chloride or silver chlorobromide Lippmann emulsion layer having an average grain size between about .01 and .05 micron and more than about 100 times slower than any of said light-sensitive silver bromoiodide emulsions, said fine-grain emulsion being coated at a coverage of about 30 to 75 milligrams of silver per square foot; and, a silver precipitating layer comprising Carey Lea silver dispersed in gelatin at a coverage of about .15 to .30 milligram silver per square foot.

5. A photographic element comprising a support having coated thereon three light-sensitive silver haloiodide emulsion layers, said layers being responsive to blue, green and red radiation and comprising, respectively, photographic couplers which form yellow, magenta and cyan dye upon reaction with oxidized color developing agent, a silver precipitating layer; and, a fine-grain silver halide emulsion layer, the halide of the fine-grain silver halide consisting essentially of chloride and bromide, the grain size of said fine-grain silver halide emulsion being less than about .1 micron and said fine-grain silver halide emulsion being at least about 50 times slower than the silver haloiodide emulsion in said light-sensitive layers, said silver precipitating layer being coated over said lightsensitive silver haloiodide emulsion layers and under said fine-grain silver halide emulsion layer.

6. A photographic element comprising a support having coated thereon, in the order given, a red-sensitive silver bromoiodide emulsion layer containing a cyan dyeforming photographic coupler; a green-sensitive silver bromoiodide emulsion layer containing a magenta dyeforming photographic coupler; a yellow filter layer; a blue-sensitive silver bromoiodide emulsion layer containing a yellow dye-forming photographic coupler; a silver precipitating layer comprising Carey Lea silver dispersed in gelatin at a coverage of about .15 to .30 milligram silver per square foot; and, a fine-grain silver bromide, silver chloride or silver chlorobromide Lippmann emulsion layer having an average grain size between about .01 and .05 micron and more than about times slower than any of said light-sensitive silver bromoiodide emulsions, said fine-grain emulsion being coated at a coverage of about 30-to 75 milligrams of silver per square foot.

7. A photographic process wherein an exposed photographic element is developed in the presence of a developer solution comprising silver halide solvent, and the photographic element is transported through the developer solution by the use of work advancing rollers immersed in the developer solution, said photographic element comprising a support having coated thereon a lightsensitive silver haloiodide emulsion and having (1) an overlying silver precipitating. layer and, between the silver precipitating layer and the silver haloiodide emulsion layer, (2) a fine-grain silver halide emulsion layer, the halide of the fine-grain silver halide consisting essentially of chloride and bromide, the size of the fine-grain emulsion being less than about .1 micron and the speed of the fine-grain emulsion being at least 50 times slower than the light-sensitive silver haloiodide emulsion.

8. A photographic process wherein an exposed photographic element is developed in the presence of a developer solution comprising silver halide solvent, and the photographic element is transported through the developer solution by the use of work advancing rollers immersed in the developer solution, said photographic element comprising a support having coated thereon three light-sensitive silver haloiodide emulsion layers, said layers being responsive to blue, green and red radiation and comprising, respectively, photographic couplers which form yellow, magenta and cyan dye upon reaction with oxidized color developing agent and having (1) an overlying silver precipitating layer and, between the silver precipitating layer and the silver haloiodide emulsion layer, (2) a fine-grain silver halide emulsion layer, the halide of the zfine-grain silver halide consisting essentially of chloride and bromide, the size of the fine-grain emulsion being less than about .1 micron and the speed of the fine-grain emulsion being at least 50 times slower than the lightsensitive silver haloiodide emulsion.

9. photographic process wherein an exposed photo graphic element is developed in the presence of a developer solution comprising silver halide solvent, and the photographic element is transported through the developer solution by the use of work advancing rollers immersed in the developer solution, said photographic element comprising a support having coated thereon, in the order given, a red-sensitive silver bromoiodide emulsion layer containing a cyan dye-forming photographic coupler; a green-sensitive silver bromoiodide emulsion layer containing a magenta dye-forming photographic couper; a yellow filter layer; and, a blue-sensitive silver bromoiodide emulsion layer containing a yellow dye-forming photographic coupler and having the following layers coated, in the order given, over said silver bromoiodide emulsion layers: (1) a fine-grain silver bromide, silver chloride or silver chlorobromide Lippmann emulsion layer having an average grain size between about .01 and .05 micron and more than about 100 times slower than any of said light-sensitive silver bromoiodide emulsions, said fine-grain emulsion being coated at a coverage of about 30 to 75 milligrams of silver per square foot; and, (2) a silver precipitating layer comprising Carey Lea silver dispersed in gelatin at a coverage of about .15 to .30 milligram silver per square foot.

10. A photographic process wherein an exposed photographic element is developed to provide an initial silver image, a reversal silver image is developed and dye is generated in proportion to the reversal silver image, and the silver images are removed from the element, said photographic element comprising a support having coated thereon a light-sensitive photographic silver bromoiodide emulsion layer and having the following layers coated, in the order given, over said silver bromoiodide emulsion layer: (1) a silver precipitating layer; and (2) a finegrain silver halide emulsion layer, the halide of the finegrain silver halide consisting essentially of chloride and bromide, the grain size of the fine-grain emulsion being less than .1 micron and the speed of the fine-grain emulsion being at least 50 times slower than the light-sensitive silver haloiodide emulsion.

11. A photographic process wherein an exposed photographic element is developed to provide initial silver images in silver bromoiodide emulsion layers, reversal silver images are developed in the silver bromoiodide emulsion layers and dye is generated in proportion to the reversal silver images, and the silver images are removed from the element, said photographic element comprising a support having coated thereon, in the order given, a redsensitive silver bromoiodide emulsion containing a cyan dye-forming photographic coupler; a green-sensitive silver bromoiodide emulsion layer containing a magenta dyeforming photographic coupler; a yellow filter layer; and, a blue-sensitive silver bromoiodide emulsion layer containing a yellow dye-forming photographic coupler, said element having the following layers coated, in the order given, over said silver bromoiodide emulsion layers: (1) a silver precipitating layer, and (2) a fine-grain silver halide emulsion layer, the halide of the fine-grain silver halide consisting essentially of chloride and bromide, the grain size of the fine-grain emulsion being less than .1 micron and the speed of the fine-grain emulsion being at least 50 times slower than the light-sensitiye silver haloiodide emulsions.

12. A photographic process wherein an exposed photographic element is developed to provide initial silver images in silver bromoiodide emulsion layers, reversal silver images are developed in the silver bromoiodide emulsion layers and dye is generated in proportion to the reversal silver images and the silver images are removed from the element, said photographic element comprising a support having coated thereon, in the order given, a redsensitive silver bromoiodide emulsion containing a cyan dye-forming photographic coupler; a green-sensitive silver bromoiodide emulsion layer containing a magenta dyeforming photographic coupler; a yellow filter layer; and, a blue-sensitive silver bromoiodide emulsion layer containing a yellow dye-forming photographic coupler, and said element having the following layers coated, in the order given, over said silver bromoiodide emulsion layers: a silver precipitating layer comprising Carey Lea silver dispersed in gelatin at a coverage of about .15 to .30 milligram silver per square foot; and, a fine-grain silver bromide, silver chloride or silver chlorobromide Lippmann emulsion layer having an average grain size between about .01 and .05 micron and more than about 100 times slower than any of said light-sensitive silver bromoiodide emulsions, said fine-grain emulsion being coated at a coverage of about 30 to milligrams of silver per square foot.

References Cited UNITED STATES PATENTS 3,353,957 11/1967 Blake 9668 3,402,046 9/1968 Zwick 9674 3,505,068 4/1970 Beckett 9668 3,523,022 8/1970 Byerley 9674 3,591,382 7/1971 Millikan 96-68 3,607,278 9/1971 Ditzer 9668 3,620,747 11/ 1971 Merchant 9674 FOREIGN PATENTS 726,137 1/1966 Canada 9674 NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner US. Cl. X.R. 9668, 76 

